Combining the sections on parasitic and fungal infections into one unit stems not so much from the similarity between parasites and fungi but rather from their not being part of the infectious diseases mainstream. From a phylogenetic perspective, parasites (even the single-cell protozoa) differ from the fungi by a considerable evolutionary distance; interestingly, based on phylogenetic analyses, the differences between protozoan parasites and fungi are less significant than the differences between protozoa and helminth parasites.